the specific spending cuts that would kick in if you didn't hit a target. well, if you can agree to those two things, you can probably agree on the broader issues. >> reporter: whatever agreement is reached, it will have to be soon. there is less than a month left until the federal government risks defaulting on its debt. darren gersh, "nightly business report," washington. >> tom: from american to european i.o.u.s-- a new page in the debt crisis overseas. moody's today cut its rating on portugal to junk, with a negative outlook. moody's fears portugal, like greece, will have trouble cutting costs and will need a second bailout. >> susie: meanwhile, an important meeting tomorrow to hammer out a bailout loan plan for greece. things were looking good for a deal until standard & poor's ratings agency warned the proposal to roll over greek government debt was in effect a "selective default." joining us now to explain what that means for investors, kenneth rogoff, professor of economics at harvard university.